The present invention relates to semiconductor devices with relatively large power capacities and, more particularly, to a semiconductor device capable of offering enhanced performances even in high temperature environments, such as within an engine room or the like. This invention also relates to an electrical power converting device using the semiconductor device along with a hybrid vehicle using this power converter.
In recent years, from standpoints of energy conservation and environmental pollution, the so-called hybrid vehicles which employ both an internal combustion engine and an electric motor and which gain the travelling drive power depending upon these both power sources and electrically powered vehicles whose travelling drive power depends on an electric motor alone attract the attention of people and are currently reduced to practice. In this case, alternate current (AC) motors, such as induction motors or synchronous motors, are often used as the electric motors, because of their merits such as high control efficiency and simplified structures.
Rechargeable batteries or capacitors are typically used as the power source in the case of hybrid vehicles. In the case of electrically powered vehicles, fuel cells are used in most cases. In any case, a conversion device for converting direct current (DC) power into AC power is required, which is called the inverter device. For this inverter, power semiconductor devices are used.
Incidentally, in the case of this power semiconductor device, aluminum wires are typically used for electrical connection between a semiconductor chip and external electrodes disposed at the periphery thereof. At this time, in high temperature environments, a problem occurs as to the cracking at contact portions of the power semiconductor chip and its associated bonding wires due to a difference in thermal expansion between the aluminum and silicon.
To prevent such cracking at the contact portions of this power semiconductor chip and the bond wires, a structure is known which uses a conductive resin material to adhere bus bar wires with a low thermal expansion material bonded thereto to upper face electrodes of power semiconductor elements (for example, see JP-A-2000-183249).